Vent stacks 22
Roof vents 24
Roof hatch 24
TV antennas 25
Lightning protection 25
Gutters and downspouts 26
Built-in gutters 26
Exterior-mounted gutters 26
Checkpoint summary 29
When inspecting a roof, you should also inspect all roof-mounted structures and projections. Specifically, look at chimneys, plumbing vent stacks, roof vents, roof hatch, skylights, TV antennas, and gutters and downspouts. Except for the last two items, an area of concern is the joint between the item and the roof. This joint, although normally sealed with flashing, is vulnerable to water leakage. With years of weathering, the flashing can develop cracks, pinholes, or breaks, resulting in periodic leaks. To correct this type of water leakage, rather than reflashing the joints, the homeowner might often seal the joints with asphalt cement. While this is an effective correction, the asphalt cement will eventually become brittle and crack, and the joints will require periodic resealing.
Chimneys are used to vent smoke and combustion gases from heating units and fireplaces. If, during your exterior inspection, you do not find a chimney, it does not necessarily mean that the house lacks a heating system. In all probability, the house is heated electrically.
Chimneys are normally constructed of masonry (brick, concrete, stone) or are prefabricated from metal or a cement-asbestos material. Masonry chimneys are usually supported by their own foundations, which in northern communities extend below the frost line. These chimneys are not dependent on the main structure for support. When inspecting a masonry chimney that extends up the side of a building, if you see open joints between the chimney and the sidewall, it is an indication of some settlement and is often not a problem. (See FIG. 3-1.) However, the open areas should be resealed. On the other hand, if the chimney is no longer vertical, it might indicate excessive settlement or the need for rehabilitation and it should be checked by a professional. Depending on the degree of settlement, the flashing at the joint between the chimney and the roof might need repair. The movement of the chimney could result in open and loose sections of flashing. (See FIG. 3-2.)
If your house has a brick chimney, look at the area above the roofline to see that it is vertical. Over the years, the mortar joints can weaken on one side and cause the chimney to lean. (See FIG. 3-3.) A leaning chimney represents a potential safety hazard, and corrective measures are needed, either bracing or rebuilding from the roofline up. If you ask the owner about the chimney, you’ll probably learn that it has been in that condition for at least fifteen years. That fact does not mean that corrective action is not needed. A leaning chimney is an indication of weakening mortar joints and should be considered of questionable structural integrity.
Sometimes brick chimneys on relatively new houses might be coated with white mineral deposits called efflorescence, a condition often caused by the absorption of water by the bricks. The minerals in the bricks dissolve in the water and then surface when the water evaporates. Although efflorescence is quite common in new brickwork, it can easily be scrubbed or washed off with a dilute solution of muriatic acid. Recurrence can usually be controlled by covering the bricks with a vapor permeable water repellant. Efflorescence on a brick chimney that has been up for many years usually means that water is getting inside the chimney, through cracks in the joints on top of the chimney or cracks in the bricks or mortar joints. If you see heavy efflorescence on an older chimney, make a note on your worksheet. The top of a masonry chimney should have a cement finish that slopes from the flue to the edge of the chimney. The purpose of this finish is to deflect rain and protect the joints between the flue and the chimney. This cement finish is vulnerable to cracking, and periodic resealing of this area should be anticipated.